The present invention includes cosmetic treatment methods and compositions, such as cosmetic and/or dermatological compositions, for preventing and/or treating sensitive and/or dry skin.
In general, sensitive skin is defined by a specific reactivity of the skin. However, as opposed to skin described as allergic, this reactivity is not the result of an immunological process, i.e., it does not occur only in skin that is already sensitized, in response to the presence of an allergen. Its mechanism is said to be aspecific.
This skin reactivity generally results in the manifestation of signs of discomfort in response to the subject coming into contact with a triggering element that may have various origins. It may involve the application of a cosmetic product at the surface of the sensitive skin, food intake or exposure to abrupt temperature variations, atmospheric pollution and/or ultraviolet or infrared rays. Associated factors such as age and the type of skin also exist. Sensitive skin is more common in dry or oily skin than in normal skin.
The appearance of these signs of discomfort, which appear within minutes after the individual has come into contact with the triggering element, is one of the essential characteristics of sensitive skin. These signs are essentially dysaesthetic sensations. The term “dysaesthetic sensations” is intended to encompass more or less painful sensations experienced in a region of skin, such as stinging, tingling, itching or pruritus, burning, heating, discomfort, tautness, etc. These subjective signs most commonly exist in the absence of visible chemical signs such as redness and desquamations. At this time, it is known that these skin irritation and intolerance reactions are associated with a release of neuropeptides by the nerve endings in the epidermis and the dermis.
EP 737 471 discloses that incorporation of certain alkaline earth metal salts into a cosmetic and/or dermatological composition makes it possible to effectively oppose the release of these neuropeptides and to advantageously obtain a preventive and/or curative effect for sensitive skin. EP 806 933 illustrates the effectiveness of strontium salts for treating irritable skin.
However, there presently is no completely satisfactory solution available for preventing and/or treating sensitive skin, and this problem is particularly exacerbated when the sensitive skin is dry skin. Dry skin manifests itself through a sensation of tautness and/or of tension and it is often associated with a decrease in the level of moisture of the skin and an impairment of barrier function, measured through an imperceptible loss of water.
WO 02/28402 describes that probiotic microorganisms can have a beneficial effect in the regulation of skin hypersensitivity reactions such as inflammatory and allergic reactions that are the result of an immunological process as opposed to the reactivity of sensitive skin. “Probiotics in the management of atopic eczema,” Clinical and Experimental Allergy 2000, Volume 30, pages 1604-1610, describes the effect of probiotics on immune mechanisms in infants, for instance atopic dermatitis.
EP 110 550 describes using bacterial agents, such as probiotics, for stabilizing and/or regulating skin ecoflora. These compounds are described as being effective for preventing the adhesion of pathogenic flora to the skin.